# Nextcloud Calendar vulnerabilities

Source: https://junglewise.ai/threats/technologies/calendar  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Updated: 9 November 2026, 03:07 UTC. Rebuilt every hour.  
Data: https://junglewise.ai/threats/technologies/calendar.json  
License: CC BY 4.0 with a link back

Junglewise Threat Intelligence has tracked 4 vulnerabilities in Nextcloud Calendar: 0 in the last 7 days and 0 in the last 90 days, 0 of them critical and 0 exploited in the wild. The most recent, CVE-2026-45286, was published on 1 June 2026.

## Counts

- Last 7 days: 0
- Last 30 days: 0
- Last 90 days: 0
- All time: 4 (0 critical, 0 exploited in the wild)

## About Nextcloud Calendar

A calendar and scheduling application integrated into the Nextcloud platform.

## Latest Nextcloud Calendar vulnerabilities

- [CVE-2026-45286: Nextcloud Calendar user enumeration via attendee suggestion endpoint](https://junglewise.ai/threats/cve-2026-45286-nextcloud-calendar-user-enumeration-via-attendee-suggestion) (medium, CVSS 4.3, published 1 Jun 2026)
- [CVE-2025-66550: Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.17 and 5.2.4, when a malicious user creates a…](https://junglewise.ai/threats/cve-2025-66550-nextcloud-calendar-is-a-calendar-app-for-nextcloud-prior-to-4-7) (medium, CVSS 5.7, published 5 Dec 2025)
- [CVE-2025-66546: Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed…](https://junglewise.ai/threats/cve-2025-66546-nextcloud-calendar-is-a-calendar-app-for-nextcloud-prior-to-4-7) (low, CVSS 3.3, published 5 Dec 2025)
- [CVE-2025-66511: Nextcloud Calendar is a calendar app for Nextcloud. Prior to 6.0.3, the Calendar app generates participant tokens for…](https://junglewise.ai/threats/cve-2025-66511-nextcloud-calendar-is-a-calendar-app-for-nextcloud-prior-to-6-0-3) (medium, CVSS 4.8, published 5 Dec 2025)

## Most severe Nextcloud Calendar vulnerabilities

- [CVE-2025-66550: Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.17 and 5.2.4, when a malicious user creates a…](https://junglewise.ai/threats/cve-2025-66550-nextcloud-calendar-is-a-calendar-app-for-nextcloud-prior-to-4-7) (medium, CVSS 5.7, published 5 Dec 2025)
- [CVE-2025-66511: Nextcloud Calendar is a calendar app for Nextcloud. Prior to 6.0.3, the Calendar app generates participant tokens for…](https://junglewise.ai/threats/cve-2025-66511-nextcloud-calendar-is-a-calendar-app-for-nextcloud-prior-to-6-0-3) (medium, CVSS 4.8, published 5 Dec 2025)
- [CVE-2026-45286: Nextcloud Calendar user enumeration via attendee suggestion endpoint](https://junglewise.ai/threats/cve-2026-45286-nextcloud-calendar-user-enumeration-via-attendee-suggestion) (medium, CVSS 4.3, published 1 Jun 2026)
- [CVE-2025-66546: Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed…](https://junglewise.ai/threats/cve-2025-66546-nextcloud-calendar-is-a-calendar-app-for-nextcloud-prior-to-4-7) (low, CVSS 3.3, published 5 Dec 2025)

## Vulnerabilities per week

Nothing was published in the last eight weeks.

| Week of | Vulns | Critical | Exploited |
| --- | --- | --- | --- |
| 17 Aug 2026 | 0 | 0 | 0 |
| 24 Aug 2026 | 0 | 0 | 0 |
| 31 Aug 2026 | 0 | 0 | 0 |
| 7 Sep 2026 | 0 | 0 | 0 |
| 14 Sep 2026 | 0 | 0 | 0 |
| 21 Sep 2026 | 0 | 0 | 0 |
| 28 Sep 2026 | 0 | 0 | 0 |
| 5 Oct 2026 | 0 | 0 | 0 |
| 12 Oct 2026 | 0 | 0 | 0 |
| 19 Oct 2026 | 0 | 0 | 0 |
| 26 Oct 2026 | 0 | 0 | 0 |
| 2 Nov 2026 | 0 | 0 | 0 |
| 9 Nov 2026 | 0 | 0 | 0 |

## Other Nextcloud technologies

- [Nextcloud Server](https://junglewise.ai/threats/technologies/nextcloud-server): 14 vulnerabilities
- [Nextcloud Enterprise Server](https://junglewise.ai/threats/technologies/nextcloud-enterprise-server): 7 vulnerabilities
- [Nextcloud Tables](https://junglewise.ai/threats/technologies/tables): 5 vulnerabilities
- [Nextcloud Approval](https://junglewise.ai/threats/technologies/approval): 4 vulnerabilities
- [Nextcloud Forms](https://junglewise.ai/threats/technologies/forms): 4 vulnerabilities
- [Nextcloud User OIDC](https://junglewise.ai/threats/technologies/user-oidc): 3 vulnerabilities

## Sources

NVD, GitHub Security Advisories, OSV, the CISA Known Exploited Vulnerabilities catalog, FIRST EPSS and vendor advisories. Rebuilt every hour. Cite as: Junglewise Threat Intelligence, "Nextcloud Calendar vulnerabilities", https://junglewise.ai/threats/technologies/calendar, 9 November 2026.